(a) Technical Field of the Invention
This invention relates generally to a method and apparatus for deactivating electronic article surveillance (“EAS”) acousto-magnetic markers, such as labels and tags. The method and apparatus disclosed herein relate to utilizing magnetic fields created by energizing electrical coils to deactivate electronic article surveillance markers.
Deactivating devices are typically used at the checkout counter in retail stores. Some devices are positioned permanently underneath the counter surface near the register at a point of sale (“POS”) where a store employee deactivates tags on merchandise that are being purchased by customers. Given their use in retail stores, there is a need for these devices to perform their function efficiently, and with minimum error. Most such deactivating devices use a coil arrangement through which current flows, thereby creating a deactivating magnetic field. The magnitude and shape of this deactivating magnetic field may be altered by factors such as changes in the strength of the current, the physical shape and composition of the coils, the number of windings used in each coil, the physical arrangement of the coils when multiple coils are used, the electrical connections between the coils, and the number of coils. It is not advisable to increase the current beyond a certain range because this may lead to excessive heat buildup. Since these devices are positioned at checkout counters, such a buildup of heat is undesirable. Increasing the number of electrical coils or the number of windings in each coil yields larger devices. Apart from being unduly costly, this is also undesirable because counter space is limited. At the same time, the deactivating magnetic field should be such that it is intense in a small area where deactivation of a tag is likely to be carried out, while reducing the negative effects of far-field magnetic strength. Similarly, it is desirable that the tags may be swiped in any orientation; that their presence within the magnetic field is sufficient to quickly trigger the sequence that leads to detection and deactivation. It is also desirable that the deactivating device is small and may be easily transported, and can be mounted at the cash register in such a way so that it offers a maximum effective area for deactivation of a tag, without interfering with other objects at the checkout counter.
(b) Description of the Relevant Art
In U.S. Pat. No. 6,778,087 for a “Dual Axis Magnetic Field EAS Device,” Belka et al. disclose a deactivator consisting of a solenoid-type coil that provides a magnetic field in one direction and another coil that provides a magnetic field in a substantially perpendicular direction, so that the EAS markers that pass through the device are positioned generally in the plane defined by the first and second directions. The magnetic fields in the two directions may be applied sequentially or simultaneously. There is also a possibility to include a third coil to create a magnetic field in a third direction that is substantially perpendicular to the plane defined by the first and second directions. This device is largely to be used for library books, videotapes, and the like, where the EAS markers are “dual-status,” i.e. they can be activated and deactivated. The device in Belka '087 works with EAS markers associated with compact discs and other optically-recorded media. Such “dual-status” markers may be activated and deactivated regardless of their orientation relative to the fields produced by the coils. The Belka device requires the markers to pass through the device, and is directed to “dual-status” markers. It is therefore different from the present invention, which is directed toward “single-status” markers, and the markers may be swiped over the device, and are detected and deactivated when swiped in any orientation.
U.S. Pat. No. 7,281,314 by Hess, et al. is for a “Method for Implementing an Antenna System.” This invention creates a multi-directional magnetic field using a single antenna. It includes a first core which could be of a standard cylindrical or rectangular shape. The core could be either an air core or a ferrite core. The first coil is cylindrically or helically wrapped around the core and forms a first antenna. The second coil may be wound transversely around the ends of the core in the shape of a rectangle or an oval, and forms a second antenna. The windings of each coil are orthogonal to each other, and so the magnetic fields generated in each coil are also orthogonal to each other. A third coil may be included. This is wrapped transversely to the first coil and the second coil. The first, second and third coil may all be wound orthogonal to each other such that the respective magnetic field will be mutually orthogonal. These antennas are used in medical applications, including implants, and are not claimed to be useful in the deactivation of EAS markers to which the present invention is directed. Thus, the Hess patent is non-analogous art.
U.S. Pat. No. 6,396,455 by Ely, et al. is for an “Antenna with Reduced Magnetic Far Field for EAS Marker Activation and Deactivation.” This invention is directed at the problem of limiting the far magnetic field. The device comprises of a rectangular core which, in some embodiments, is formed from powdered iron. A first coil is wrapped spirally about an axis of the core in a rotational direction; a second coil is wrapped spirally about the same axis of the core in a rotational direction counter to the first rotational direction; these two are combined to form a coil arrangement. Similarly, a third and fourth coil may be wrapped in like manner around the second axis of the core. These coil arrangements are then driven by a decaying alternating current to produce a decaying, alternating magnetic field for deactivation of EAS markers. The two coil arrangements here have independent current sources.
Another device to deactivate “dual-status” markers is disclosed in U.S. Pat. No. 5,341,125 by Plonsky, et al. for a “Deactivating Device for Deactivating EAS Dual Status Magnetic Tags.” This device comprises a deactivator pad with a detection transmitting coil, a detection receiving coil, and a deactivating coil, all of which are in a substantially parallel or coplanar relationship. The detection transmitting coil is planar and of circular configuration. The deactivating coil could be inscribed within the detection transmitting coil or could circumscribe it. The detection receiving coil includes two adjacent planar coils that are parallel to the detection transmitting coil and the deactivation coil. The deactivating electromagnetic field has components in each of the three mutually orthogonal planes. The main object of this invention is to simultaneously detect and deactivate a tag.
U.S. Pat. No. 5,805,065 by Schwarz, et al. is for an “Electro-Magnetic Desensitizer”. This invention relates to detection of the security marker and its deactivation. An electromagnetic coil is wrapped around a U-shaped yoke. The legs of the U-shaped yoke may fill the top of the coil to concentrate the magnetic field at the top of the coil. The entire apparatus may be mounted under the top of a cash register table so that the operator simply has to move an item with a tag across the table top to deactivate it.
U.S. Pat. No. 6,084,515 by Maitin, et al. is for a “Coil Array for EAS Marker Deactivator.” The device consists of several substantially planar substrates stacked one on top of the other. Each planar substrate may be in the shape of a square, and consists of an array of spiral coils. All the coils in all the substrates are electrically connected together in series.
U.S. Pat. No. 5,142,292 by Chang, et al. is for a “Coplanar Multiple Loop Antenna for Electronic Article Surveillance Systems.” The antenna includes a substantially planar dielectric substrate with conductive loops that are not coils, but are etched in the substrate, and are electrically connected in series. The entire device facilitates the deactivation of a tag oriented in any direction with respect to the antenna.
U.S. Pat. No. 5,917,412 by Martin is for a “Deactivator with Biplanar Deactivation.” This device has two coil parts; the first one is positioned in angular adjacent relation to the second coil part, so that together they transmit a simultaneous deactivation field. Preferably, the first deactivating coil is positioned so that its plane is at an angle in the range of 45° to 135° with respect to the plane of the second deactivating coil. A similar device is disclosed in U.S. Pat. No. 7,374,092 by Acosta, et al. for a “Combined Data Reader and Electronic Article Surveillance (EAS) System.” Here the deactivation modules may have various configurations such as planar coils, a magnetically active core with coil windings, or two part L-shape construction. The coils are housed in two separate units, one horizontal, and the second unit is placed at a suitable angle to the first unit. The two units may or may not be physically and/or electrically connected. U.S. Pat. No. 7,495,564 by Harold, et al. for “Systems and Methods for Data Reading and EAS Tag Sensing and Deactivating at Retail Checkout,” discloses a device with one or more deactivating coils positioned in a variety of different angles and positions, depending on the shape of the deactivation zone desired to be formed. The deactivation unit itself comprises a central core of magnetically active material with outer wire windings through which current is passed to create the deactivating magnetic field. In U.S. Pat. No. 5,867,101 by Copeland, et al. for a “Multi-Phase Mode Multiple Coil Distance Deactivator for Magnetomechanical EAS Markers,” the deactivating device consists of first, second, third and fourth rectangular coils arranged in a two-by-two array in a common plane. Two sets of coils are driven out of phase or in phase to achieve different magnetic fields. The coplanar coil arrangement can be adapted to the geometry of the checkout counter. For instance, one of the coils may be rotated out of the coplanar arrangement.
While the inventions mentioned above are mostly directed at various methods to deactivate tags or markers, they fail to achieve the advantages offered by the present invention. Many prior art devices for the deactivation of EAS markers require the tag to be swiped in a particular orientation or in a preferred direction. The shape and strength of the deactivating magnetic field in the prior art devices often requires the tag to be very close to the deactivator, or to physically touch the deactivating surface. These devices are often bulky and occupy a large portion of the counter space at the point of sale. Traditionally, deactivators or scanners must physically touch a label to deactivate it. But with the growing use of source tagging wherein the identification tags are hidden somewhere on an item or in its packaging, proximity deactivators or distance deactivators, or verifiers that don't require contact with a label, are becoming more important. The device of the present invention is a distance deactivator designed for flush mounting into the countertop, and the device improves throughput by quickly scanning and deactivating labels in all orientations. As a distance deactivator, the label need not come in contact with the deactivator; simply passing it over the deactivator is all that it takes. Since most EAS markers operate in the frequency range of 58,000 Hertz (58 Khz), this invention is designed to deactivate such markers.
High throughput, simplicity and a subtle presence are the main characteristics of this device. It is designed for flush mounting which conserves space, and allows for ease of merchandise movement over the counter. Simplicity means that there are no buttons to push and no lights to look at. A distinctive sound indicates the presence and deactivation of the label. High throughput means that the delays normally experienced by competitor products are easily avoided. This module interfaces the deactivator to the POS register, where the user can enable/disable the deactivation function right from the register.